This invention relates to an improved thermoplastic coated paperboard carton and, more particularly, it is directed to a carton and to a blank for constructing the carton so as to include a gable-top closure having an upstanding ridge with a recessed upper edge to minimize the effects of a weeper condition during transport.
In the packaging of liquids, such as milk, orange juice, and other dairy and juice products, considerable use is made of gable-top cartons formed of polyethylene coated paperboard.
One situation that presents a problem to the packaging industry is the difficulty encountered in maintaining carton integrity when the liquid product is shipped over a great distance between the dairy or bottler and the customer. Repetitive physical contact or rubbing caused by shipping vibrations between, say, two stacked layers of gable-top cartons can aggravate a possible pre-existing weeper condition in the carton bottoms of an upper layer of cartons during transport.
A "weeper" describes a situation that occurs when liquid product drips from the container. It is different than a leaking carton which involves the escape of product by way of flow through an area where two pieces of board were poorly sealed together. In a weeper situation, product gets into the board by way of a hole in the inside polyethylene coating. The product saturates the board and seeps or weeps through the outside polyethylene coating before it works its way out of the carton.
During carton formation, bottom closure panels or flaps sometimes puncture the inside polyethylene coating and become embedded in the adjacent board. This creates a weeper condition. Eventually, liquid product will enter the puncture, saturate the board and outside coating, and weep from the carton.
If a weeper condition exists, the vibrations that are normally encountered during transport aggravate the situation further. Because the bottom of a filled carton has a tendency to bulge outwardly, especially in the central area of such bottom, a recessed top construction according to the present invention will minimize contact between vertically stacked gable-top cartons by permitting the bottom of the top carton to be supported at the ends of the upstanding rib or ridge of the bottom carton instead of the central portion thereof. This will reduce the amount of rubbing, and the physical damage caused thereby, that usually occurs at the sensitive central bottom area of the carton being supported.